Fluorescent detectors for hydroxyl radical and their applications in bioimaging: A review

Among various reactive oxygen species (ROS), hydroxyl radical (·OH) has the strongest oxidizability, which causes damage to a wide array of biomacromolecules in the cells, including DNA, lipid, and proteins. Therefore, the over-produced ·OH is verified to be implicated in various oxidative-stress related pathophysiological processes, such as inflammation, cancer, and cardiovascular disorder. However, the precise pathogenic roles played by this substance have been far from being clearly understood due to its high reactivity, short lifetime, and low concentration in biosystems. Thus, developing highly sensitive and selective detecting tools for monitoring ·OH is of significant importance. This review summarizes the advances that have been made in the last decade in the development of fluorescent sensors for ·OH detection based on small molecules and nanoparticles as well as their diverse biological applications.